EMG signals can be widely used for indicators of muscle activity, and it can be used for robot control. However, the practical use of the EMG sensor for the amputee has been limited due to harsh conditions in the socket where strong pressure and friction exist. In this paper, thus we suggested a flexible and stretchable EMG Sensor. It is designed to withstand the pressure of the socket and to be used repeatedly with soft adhesive material. The performance of mechanical and electrical properties is investigated, and the muscle signals are recorded in static and dynamic (jump and gait) conditions. The selectivity of the recorded muscle signals during dorsiflexion and plantar flexion shows better than that of commercial electrodes indicating that it could be used for control of robotic legs in the future.Clinical Relevance- The flexible material and stretchable electrode pattern could be helpful in clinical research for an amputee.